What's a good Android app for drilling down on math and language arts skills, like, REALLY drilling down?

Okay, so IXL. I initially checked it out because my niece was using it, and I wanted to see if it was actually helping or just another digital babysitter. Turns out, it's statistically satisfying. They've got skills broken down into tiny, manageable chunks, and the progress tracking is intense – in a good way. I'm talking detailed reports you can actually export to CSV in under 10 seconds. The dashboard actually makes sense, which is a huge win. Plus, the graphs are actually readable, unlike some of the stuff I see at work (seriously, who designs those things?). I haven't dug into the API capabilities yet, but I'm betting there's some interesting data you could pull out for further analysis. If you're looking for something that generates clean datasets, this is it. Finally, goodbye to Excel hell for tracking my niece's progress! It's like Tableau but for normal humans.